I prefer to give my tenants a little bit more comfort and decent amenities (esp for 80sqm which is a decent size for middle class and above tenants who are quite demanding in terms of quality) so minimum spend would be about 25k per sqm.
Decent amenities meaning
-600 mm tiles
- quality cupboards and finishings
-classy light fixtures
- nice wardrobes
- decent sanitary ware
Etc.
You can charge a premium due to quality and these tenants are more long term and reliable imho
In the final analysis, it all boils down to sheer plain old hard work and dogged persistence. Nothing more, nothing less!!